Produsentens info: "Hi-Lift forged rockers on our special rocker shafts for road or race. Ensure you tighten down all posts equally to eliminate stress fractures on shaft Using 1.5 ratio high lift rockers has almost become the standard amongst engine tuners and these are more effective at high revs than roller type which are also very expensive. Mini Spares 1.5 ratio forged rockers set are a direct replacement for the standard versions and will give significant gains on 1275cc units. Complete kit includes eight rockers, adjusting screws, four steel pedestals and heavy duty rocker shaft. Tighten posts evenly to stop potential fracturing of rocker shaft. The most often talked about "high lift rockers" are the latest design "roller" type (seeC-AHT438, but the main reason "high lift" rockers were designed was to allow easy bolt on performance without having to disassemble the engine to change camshafts. This performance improvement is achieved with or without the "roller" added option. The standard "high lift" rockers provide a ratio of 1.5 vs the stock 1.25. (The "roller tip" type also have a 1.5 ratio). Valve clearances should be opened up by .003" over recommended settings, although up to .005" can prove beneficial with certain combinations. Using the 1.5 ratio not only increases the maximum lift, but it also means that the valve is open approximately 20% more at any given point- although opening and closing periods remain the same. This vastly improves volumetric efficiency and therefore power output. "